Magnor Marcus, Kindlmann Gordon, Hansen Charles, Duric Neb
MPI Informatik, Stuhlsatzenhausweg 85, 66123 Saarbrücken, Germany.
IEEE Trans Vis Comput Graph. 2005 Sep-Oct;11(5):485-96. doi: 10.1109/TVCG.2005.84.
From our terrestrially confined viewpoint, the actual three-dimensional shape of distant astronomical objects is, in general, very challenging to determine. For one class of astronomical objects, however, spatial structure can be recovered from conventional 2D images alone. So-called planetary nebulae (PNe) exhibit pronounced symmetry characteristics that come about due to fundamental physical processes. Making use of this symmetry constraint, we present a technique to automatically recover the axisymmetric structure of many planetary nebulae from photographs. With GPU-based volume rendering driving a nonlinear optimization, we estimate the nebula's local emission density as a function of its radial and axial coordinates and we recover the orientation of the nebula relative to Earth. The optimization refines the nebula model and its orientation by minimizing the differences between the rendered image and the original astronomical image. The resulting model allows creating realistic 3D visualizations of these nebulae, for example, for planetarium shows and other educational purposes. In addition, the recovered spatial distribution of the emissive gas can help astrophysicists gain deeper insight into the formation processes of planetary nebulae.
从我们受限于地球的视角来看，一般而言，确定遥远天体的实际三维形状极具挑战性。然而，对于一类天体来说，仅从传统二维图像就能恢复其空间结构。所谓的行星状星云（PNe）展现出因基本物理过程而产生的显著对称特征。利用这种对称约束，我们提出一种从照片自动恢复许多行星状星云轴对称结构的技术。基于GPU的体绘制驱动非线性优化，我们估计星云的局部发射密度作为其径向和轴向坐标的函数，并恢复星云相对于地球的方向。该优化通过最小化渲染图像与原始天文图像之间的差异来完善星云模型及其方向。所得模型可用于创建这些星云的逼真三维可视化效果，例如用于天文馆展示及其他教育目的。此外，恢复的发射气体空间分布有助于天体物理学家更深入地了解行星状星云的形成过程。
